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Updated June 13, 2014

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Definition: Cyanosis is a bluish, grayish, or dark purple discoloration of the skin and/or mucus membranes which is caused by a deficiency of oxygen and an excess of carbon dioxide in the blood. Cyanosis may occur secondary to any condition that interferes with the ability of air to enter the respiratory tract, or due to an overdose of certain drugs or asphyxiation.

The color of your skin is determined by the amount of pigment it contains and the blood flowing through it. Blood that is rich with oxygen is bright red. Blood that is lacking in oxygen is darker, more bluish-red in color. People who are lacking oxygen in their blood may suffer from cyanosis.

Causes of Cyanosis

Cyanosis can be caused by a wide variety of disorders, including but not limited to:

Most Common Places That Cyanosis May Appear

Mild cyanosis may be difficult to detect even in light-skinned people. In fact, it may not manifest itself on the skin until the oxygen saturation drops well below 90%. In dark-skinned people, cyanosis may be easier to detect in the mucus membranes such as the lips, gums, nail beds or around the eyes.

When to Contact a Health Care Professional

Cyanosis may be a sign of a serious medical condition. If you are an adult and have cyanosis, call your doctor or 911 if you experience any of the following:

  • Chest pain (automatic 911 call)
  • Your breathing gets harder or faster and you are unable to take a deep breath
  • You need to lean forward to breathe when sitting
  • You are using the muscles around your ribs, neck or shoulders to help you breathe
  • You are experiencing frequent headaches
  • You are more sleepy or confused than usual
  • You have a fever
  • You start to cough up dark mucus
Pronunciation: si-a-no-sis
Also Known As: skin discoloration, blue skin
Common Misspellings: sianosis, cianosis
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